The Second Law of Thermodynamics. 27/10/05

Look at the definitions of the 2nd law and select those which you feel are most meaningful. For example, look at Kelvin-Planck and Clausius.
When asked to define Entropy, it`s important that you stay on course and be content to give a definition that is sufficient and remains relevent to the work for this part of the course.
Think of the reversible adiabatic process and the significance of entropy in this context.
Use the Carnot cycle to give an example of a heat transfer processes that can be considered reversible.
What processes make up the Carnot cycle?
Can you explain how it is impossible for an engine to achieve 100% efficiency?

Heat energy and work energy are mutually convertible one into the other but there is an important difference. Mechanical work can be completely converted into heat energy but heat energy cannot be completely converted into work.
Therefore in the Carnot cycle, there is always a loss to a colder body and the efficiency of an engine can never be 100%.

The 2nd Law indicates the way in which heat can be converted to mechanical work.